Fluid pump with flow control means

ABSTRACT

A fluid pump including a plurality of expansible chambers and a bypass flow control valve for directing fluid flow from the outlet of selected chambers to the inlet of the other chambers when the output flow of all the pump chambers is above a predetermined value.

United States Patent [191 Johnson et al. v

[451 Jan. 29, 1974 FLUID PUMP WITH FLOW CONTROL MEANS Inventors: David E. Johnson; Frederick Rehield, both of Saginaw, Mich.

Assignee: General Motors Corporation,

Detroit, Mich.

Filed: June 15, 1972 Appl. No.: 263,167

US. Cl. 417/62, 418/8 Int. Cl. F04b 23/04, F040 23/00 Field of Search 417/62, 248; 418/8 References Cited UNITED STATES PATENTS Eames 417/62 2,904,012 9/1959 Hazen 417/62 X 3,207,077 9/1965 Zeiglr 417/300 3,381,891 5/1968 Bellmer 417/62 Primary Examiner-C. J. Husar Assistant Examiner-Leonard Smith Attorney, Agent, or F irm'- D. F. Scherer 57 ABSTRACT A fluid pump including a plurality of expansible chambers and a bypass flow control valve for directing fluid flow from the outlet of selected chambers to the inlet of the other chambers when the output flow of all the pump chambers is above a predetermined value.

4 Claims, 3 Drawing Figures FLOW 5 CONTROL PATENTEUJANZSIHM $788,770

I I I a FLOW fi CONTRO L.

FLUID PUMP WITH FLOW CONTROL MEANS This invention relates to fluid pumps and controls therefor and more particularly to fixed displacement pumps having flow control means for maintaining a substantially constant pump flow with varying pump speeds.

In prior art flow controlled pumps including flow control valves which bypass excessive fluid flow from the pump outlet to the pump inlet, all of the unused and bypassed flow undergoes a pressure decrease determined by the system pressure requirements as it passes through the flow control valve thereby generating heat in the fluid system and substantially reducing the efficiency of the pump particularly at high pump speeds. The present invention reduces the heat generated by bypassing a portion of the pump output flow at low pump output pressures while the remaining pump flow is delivered through a secondary flow control valve at a higher pressure as required by the system being operated. This is particularly useful in power steering pumps driven by automotive engines having variable output speeds especially when the pump is driven at high engine speeds.

It is therefore an object of this invention to provide in an improved fluid pump having a plurality of expansible chambers a flow control valve operable to direct fluid flow from selected chambers to the inlet of the other chambers thereby reducing heat generated and increasing pump efficiency.

Another object of this invention is to provide in an improved flow control pump having a plurality of expansible fluid chambers a control valve for providing a parallel fluid flow from selected chambers to the remaining chambers which are connected to the pump output under low flow conditions and a series fluid connection between the output of the selected chambers to the input of the remaining chambers when the fluid flow is above a predetermined value.

A further object of this invention is to provide in an improved flow controlled pump having a plurality of expansible chambers a valve for connecting the outlet of selected chambers to the outlet of the remaining chambers which are connected with the pump outlet below a predetermined fluid flow and for connecting the outlet of the selected chambers with the inlet of the remaining chambers when the fluid flow is above the predetermined value.

These and other objects and advantages of the present invention will be more apparent from the following description and drawings in which:

FIG. I is a schematic representation of a fluid system incorporating the invention;

FIG. 2 is a cross sectional view of a pump and flow control valve embodying the invention; and

FIG. 3 is a partial view in cross section of the flow control valve shown in FIG. 2.

Referring to the drawings there is shown in FIG. 1 a vane type pump generally designated having inlet ports 12 and 14 in parallel fluid communication with a reservoir 16 via passage 18 and via passage 20 and a check valve 22, respectively. The pump 10 has an outlet port 24 in series flow relationship with inlet port 14 and also in fluid communication with a flow control valve generally designated 26 via passage 28. The flow control valve 26 is a conventional pressure compensated flow control valve which is operable to deliver a predetermined amount of fluid to a fluid system via passage 30 and bypass the remaining flow in passage 28 to the reservoir 16 via passage 32. The pump 10 has a second output port 34 which is in a series flow relationship with inlet port 12 and also in fluid communication via passage 36, a restriction 38 and a passage 40 with a bypass flow control valve generally designated 42. The bypass flow control valve 42 has two outlet ports 44 and 46 connected to passages 28 and 20, respectively.

The bypass flow control valve 42 is spring biased to the position shown by a spring 50 and is movable to a second position by action of fluid pressure operating on the valve 42. The fluid pressure on the end of valve 42 opposite the spring 50 is supplied via passage 52 and is equal to the pressure in passage 36 upstream of the restriction 38. The fluid pressure acting on the other end of valve 42 is equal to the fluid pressure in the restriction 38 and is supplied via passage 54. When the fluid flow delivered by the pump 10 to passage 36 is below a predetermined value the fluid pressure in passages 52 and 54 will be substantially equal and the spring 50 will maintain the valve 42 in the position shown. However, as the fluid flow from port 34 increases a pressure differential between passages 52 and 54 is established by fluid flow through the restriction 38 thereby decreasing the fluid pressure in passage 54 relative to the fluid pressure in passage 52. When the fluid pressure in passage 52 acting on the end of valve 42 provides a force greater than the fluid pressure in passage 54 and the spring 50, which supply opposing forces to the valve 42, the valve 42 will be shifted to the second position. The point at which the valve shifts will be determined by the pressure decrease of the fluid flowing through the restriction 38 and the pre-load force in the spring 50. By controlling these variables, spring 50 and the size of restriction 38, the valve 42 can be made to operate at a predetermined flow in passage 36.

In the position shown the valve 42 provides fluid communication between the output 34 and the passage 28 in parallel relationship with the flow from output 24 such that the entire output of pump 10 is delivered to the flow control valve 26 at a pressure determined by the work requirement of the fluid system supplied by passage 30. As discussed above, the entire flow and passage 28 will not be delivered to the passage 30 due to theoperation of the flow control valve 26, therefore, a portion of the pump flow is directed back to the reservoir l6 and the power required by the pump to deliver the excess flow is dissipated in the form of heat which reduces the efficiency of the pump. When the bypass flow control valve 42 is in the second position the output flow from port 34 is directed to the input port 14 thereby placing the output ports 34 and 24 in series re lationship. The check valve 22 prevents the fluid from port 34 being directed to the reservoir 16. The pump pressure necessary to deliver the fluid from port 34 to port 14 is determined by the pressure required to force the oil through the restriction 38. This pressure requirement is substantially less than the pressure requirement of passage 30 and the restriction requirement of flow control valve 26. Therefore, the heat generated and the power dissipated is considerable less which results in an increase in pump efficiency.

The pump 10 is a conventional dual lobe pressure balanced vane type pump having a plurality of expansible chambers 56 formed by a pump rotor 58, a cam 60 and a plurality of vanes 62. The chambers expand and contract as the pump rotor 58 is driven. The chambers 56 expand as they pass ports 12 and 14 to draw fluid into the chambers 56'and contract as they pass ports 24 and 34 to expel fluid from the chambers to passages 28 and 36, respectively. Preferably, the pump provides equal fluid displacement between inlet and outlet ports 12 and 34 and inlet and outlet ports 14 and 24. Therefore, the fluid flows delivered to outlet ports 24 and 34 are equal. Also the fluid flow delivered by port 34 is equal to the fluid intake at port 14. By way of example, it is assumed the flow control valve 26 is designed to deliver fluid at the rate of three gpm to the passage 30 and bypass excessive flow. The pump 10 is designed to have a displacement of one cu. in. per revolution and therefore the ports 34 and 24 each deliver one-half cu. in. per revolution. With this displacement design, the pump 10 will deliver approximately three gpm at 700 rpm. Thus, when the pump is driven above 700 rpm the flow control valve 26 will be operable to bypass fluid. The bypass on flow control valve 42 is also designed to bypass all the fluid from port 34 when the flow therefrom is at three gpm, or more. When the pump speed is at approximately 1,400 rpm three gpm will be delivered from each port 34 and 24. At this point the bypass flow control valve 42 will be operable to deliver the fluid flow from port 34 to port 14 at a substantially reduced pressure and the fluid flow from port 24 will pass through the flow control valve 26. As the pump speed is increased above 1,400 rpm, the fluid flow from port 34 will continue to be bypassed to the port 14 via valve 42 and the flow from port 24 will be divided by the flow control valve 26 to deliver three gpm to passage 30 and the remaining fluid will be bypassed to reservoir 16. Since the fluid flow from port 34 is equal to the fluid intake of port 14 the possibility of cavitation, which can occur at high fluid flows in positive displacement pumps, is substantially reduced.

The pump shown in FIG. 2 is a positive displacement vane type pump similar in construction to the pump described in the US. Pat. to Zeigler et al. No. 3,207,077 issued Sept. 21, 1965. The pump includes a pump housing 70 which rotatably supports a pump drive shaft 72 which is drivingly connected through splines 74 to a pump rotor 76. The pump rotor 76 is positioned between a pair of end plates 78 and 80 which are positioned in the pump housing 70 by a pair of pins 82. The pins 82 also position a cam ring 84 in the pump housing 70. The rotor 76 has a plurality of slots 86 in which are slidably disposed vanes 88 which cooperate with the rotor 76, the end plates ,78 and 80 of the cam ring 84 to form a plurality of expansible fluid chambers. The fluid chambers expand and contract upon rotation of the pump rotor 70 to deliver fluid to a pair of outlet chambers 90 and 92 formed in the end plate 78. The chambers are supplied with fluid from a reservoir 93, formed between the pump housing 70 and a sheet metal cover 95, through a pair of inlet ports, not shown. The chambers 90 and 92 are in fluid communication with a pressure plate 94 which has an output fluid chamber 96 in fluid communication with a pump outlet port 97.

A bypass flow control valve generally designated 98 is disposed in the pressure plate 94 and includes a poppet valve 100 and a bias spring 102. The poppet valve 100 has a sealing edge 104 which prevents fluid communication between chambers 90 and an inlet passage 106 when the poppet valve 100 is biased to the closed position by the spring 102. The inlet passage 106 is in fluid communication with the pump inlet port which supplies the fluid that is expelled from the pump through outlet chamber 92. The poppet valve 100 also has a plurality of axial passages 108 which are in fluid communication through a chamber 110 to an outlet port 1 12. The outlet port 112 is in fluid communication through a reed type check valve 114 with the pump outlet 98. Fluid flow from the chamber passes through a port 116 and across a face 118 on the end of poppet valve to the axial passages 108. The outlet port 116 is formed in a separater plate 120 which is in close proximity with the face 118 such that fluid flow through port 116 to passages 108 must pass through a restricted area 122 thereby causing apressure decrease between port 116 and passages 108. As a result of the pressure decrease caused by the restriction 122, the pressure operating on face 118 will be greater than the pressure in chamber 1 10. This pressure differential will increase as the flow through port 116 increases until the pressure differential across the restriction 122 causes a pressure drop sufficient for the pressure acting on face 118 to overcome the force in spring 102 and the pressure in chamber 1 l0 acting on the poppet valve 100. When this pressure differential occurs the poppet valve will be moved against the spring 102 thereby permitting fluid flow from the port 116 to the inlet passage 106. When the poppet valve 100 is opened the fluid flow past the face 118 and the sealing edges 104 will result in a further decrease in pressure in chamber 110 due to the radial fluid flow past the passages 108, and the resulting Bernoulli effect, thereby causing the poppet valve 100 to open further. When the poppet valve 100 has opened the reed type check valve 114 will close preventing a back flow from chamber 96 to chamber 1 10 and all of the fluid flow from chamber 90 will be directed back to the pump inlet.

The pump output 97 includes a system flow control valve similar in design to that shown in the abovementioned Zeigler et al. patent which operates to deliver a predetermined amount of fluid from the pump to the system in which it is to operate. Excess fluid flow is directed by the system flow control valve to the pump inlet. The bypass flow control valve 98 can be designed to operate in accordance with the system discussed above for FIG. 1. That is, until the total fluid flow from chambers 92 and 90 is equal to twice the desired fluid flow from the pump. The chambers 90 and 92 will deliver fluid in parallel to the pump output 97. When the fluid flow from chambers 90 and 92 is twice the amount desired from the pump output, the fluid flow from the chamber 90 will be directed via the bypass flow control valve 98 to the inlet of the pump chambers which deliver fluid to the chamber 92 thusplacing the chambers 90 and 92 in series relationship.

Obviously, many modifications and variations of the present invention are possible in light of the .above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A fluid pump comprising a plurality of expansible fluid chambers; first and second inlet port means for selectively communicating fluid to said fluid chambers during expansion thereof; first and second outlet port means for selectively communicating fluid from said fluid chambers during contraction thereof; pump outlet port means in continuous fluid communication with said first outlet port means for directing fluid from said pump; first flow control valve means in fluid communication with said pump outlet port means for limiting the fluid flow from said pump at a predetermined level; and second flow valve means in fluid communication with said second outlet port means and being responsive to fluid flow from said second outlet port means to direct fluid flow therefrom to said pump outlet means when said fluid flow from said second outlet port means is below the level determined by said first flow control valve means, and to direct fluid flow from said second outlet port means to said first inlet port means when the fluid flow therefrom is above the predetermined level of said first flow control valve means.

2. A fluid pump comprising a plurality of expansible fluid chambers; first and second inlet port means for selectively communicating fluid to said fluid chambers during expansion thereof; first and second outlet port means in series fluid relationship with said first and second inlet port means respectively for selectively communicating fluid from said fluid chambers during contraction thereof; pump outlet port means in continuous fluid communication with said first outlet port means for directing fluid from said pump; first flow control valve means in fluid communication with said pump outlet port means for limiting the fluid flow from said pump at a predetermined level; and second flow valve means in fluid communication with said second outlet port means and being responsive to fluid flow from said second outlet port means to direct fluid flow therefrom to said pump outlet means in parallel fluid flow relationship with said first outlet port means when said fluid flow from said second outlet port means is below the level determined by said first flow control valve means, and to direct fluid flow from said second outlet port means in a series fluid relationship with said first inlet port means when the fluid flow therefrom is above the predetermined level of said first flow control valve means.

3. A fluid vane pump comprising a pump rotor; a plurality of vanes slidably disposed in said rotor; dual lobe cam means surrounding said rotor and cooperating with said rotor and vanes to form a plurality of expansible chamber; drive means for rotating said rotor relative to said cam means for expanding and contracting said chambers twice during each revolution of said ro tor; reservoir means for storing fluid; first and second inlet port means in parallel flow relationship for directing fluid to said chambers from said reservoir means; first and second outlet port means in series flow relationship with said first and second inlet port means respectively; pump outlet port means for directing fluid flow from said pump in continuous fluid communication with said first outlet port means; pump flow control means in fluid communication with said pump outlet port means for limiting the fluid flow from said fluid vane pump at a predetermined level; and bypass and flow control valve means including slidable valve means in fluid communication with said second outlet port means and being responsive to fluid flow from said second outlet port to direct the fluid flow therefrom to said pump outlet port means when the fluid flow from said second outlet port means is below the level determined by said pump flow control valve means, and to direct fluid flow therefrom to said first inlet port means when the fluid flow from said second outlet port means is at or above said predetermined level.

4. A fluid vane pump comprising a pump rotor; a plurality of vanes slidably disposed in said rotor; dual lobe cam means surrounding said rotor and cooperating with said rotor and vanes to form a plurality of expansible chambers; drive means for rotating said rotor relative to said cam means forexpanding and contracting said chambers twice during each revolution of said rotor; reservoir means for storing fluid; first and second inlet port means in parallel flow relationship for directing fluid to said chambers from said reservoir means; first and second outlet port means in series flow relationship with said first and second inlet port means respectively; pump outlet port means for directing fluid flow from said pump in continuous fluid communication with said first outlet port means; pump flow control valve means in fluid communication with said pump outlet port means for limiting the fluid flow from said fluid vane pump at a predetermined level; bypass and flow control valve means including slidable valve means in fluid communication with said second outlet port means, restriction means disposed between said second outlet port means and said slidable valve means, first passage means downstream of said restriction means in fluid communication with said pump outlet port means for directing fluid flow from said second outlet port means to said pump outlet port means when the fluid flow from said second outlet port means is below the predetermined level of said pump flow control valve means; second passage means downstream of said restriction means for directing fluid flow from said second outlet port means to said first inlet port means when the fluid flow from said second outlet port means is above the predetermined level of said pump flow control valve means and pressure responsive means on said slidable valve means responsive to fluid flow from said second outlet port means and through said restriction means for moving said slidable valve means to provide fluid communication between said second outlet fluid flow from said second outlet port means is above the predetermined level. 

1. A fluid pump comprising a plurality of expansible fluid chambers; first and second inlet port means for selectively communicating fluid to said fluid chambers during expansion thereof; first and second outlet port means for selectively communicating fluid from said fluid chambers during contraction thereof; pump outlet port means in continuous fluid communication with said first outlet port means for directing fluid from said pump; first flow control valve means in fluid communication with said pump outlet port means for limiting the fluid flow from said pump at a predetermined level; and second flow valve means in fluid communication with said second outlet port means and being responsive to fluid flow from said second outlet port means to direct fluid flow therefrom to said pump outlet means when said fluid flow from said second outlet port means is below the level determined by said first flow control valve means, and to direct fluid flow from said second outlet port means to said first inlet port means when the fluid flow therefrom is above the predetermined level of said first flow control valve means.
 2. A fluid pump comprising a plurality of expansible fluid chambers; first and second inlet port means for selectively communicating fluid to said fluid chambers during expansion thereof; first and second outlet port means in series fluid relationship with said first and second inlet port means respectively for selectively communicating fluid from said fluid chambers during contraction thereof; pump outlet port means in continuous fluid communication with said first outlet port means for directing fluid from said pump; first flow control valve means in fluid communication with said pump outlet port means for limiting the fluid flow from said pump at a predetermined level; and second flow valve means in fluid communication with said second outlet port means and being responsive to fluid flow from said second outlet port means to direct fluid flow therefrom to said pump outlet means in parallel fluid flow relationship with said first outlet port means when said fluid flow from said second outlet port means is below the level determined by said first flow control valve means, and to direct fluid flow from said second outlet port means in a series fluid relationship with said first inlet port means when the fluid flow therefrom is above the predetermined level of said first flow control valve means.
 3. A fluid vane pump comprising a pump rotor; a plurality of vanes slidably disposed in said rotor; dual lobe cam means surrounding said rotor and cooperating with said rotor and vanes to form a plurality of expansible chamber; drive means for rotating said rotor relative to said cam means for expanding and contracting said chambers twice during each revolution of said rotor; reservoir means for storing fluid; first and second inlet port means in parallel flow relationship for directing fluid to said chambers from said reservoir means; first and second outlet port means in series flow relationship with said first and second inlet port means respectively; pump outlet port means for directing fluid flow from said pump in continuous fluid communication with said first outlet port means; pump flow control means in fluid communication with said pump outlet port means for limiting the fluid flow from said fluid vane pump at a predetermined level; and bypass and flow control valve means including slidable valve means in fluid communication with said second outlet port means and being responsive to fluid flow from said second outlet port to direct the fluid flow therefrom to said pump outlet port means when the fluid flow from said second outlet port means is below the level determined by said pump flow control valve means, and to direct fluid flow therefrom to said first inlet port means when the fluid flow from said second outlet port means is at or above said predetermined level.
 4. A fluid vane pump comprising a pump rotor; a plurality of vanes slidably disposed in said rotor; dual lobe cam means surrounding said rotor and cooperating with said rotor and vanes to form a plurality of expansible chambers; drive means for rotating said rotor relative to said cam means for expanding and contracting said chambers twice during each revolution of said rotor; reservoir means for storing fluid; first and second inlet port means in parallel flow relationship for directing fluid to said chambers from said reservoir means; first and second outlet port means in series flow relationship with said first and second inlet port means respectively; pump outlet port means for directing fluid flow from said pump in continuous fluid communication with said first outlet port means; pump flow control valve means in fluid communication with said pump outlet port means for limiting the fluid flow from said fluid vane pump at a predetermined level; bypass and flow control valve means including slidable valve means in fluid communication with said second outlet port means, restriction means disposed between said second outlet port means and said slidable valve means, first passage means downstream of said restriction means in fluid communication with said pump outlet port means for directing fluid flow from said second outlet port means to said pump outlet port means when the fluid flow from said second outlet port means is below the predetermined level of said pump flow control valve means; second passage means downstream of said restriction means for directing Fluid flow from said second outlet port means to said first inlet port means when the fluid flow from said second outlet port means is above the predetermined level of said pump flow control valve means and pressure responsive means on said slidable valve means responsive to fluid flow from said second outlet port means and through said restriction means for moving said slidable valve means to provide fluid communication between said second outlet port means and said second passage means when the fluid flow from said second outlet port means is above the predetermined level. 